Boost Your Java Docs: Quickly Create UML Diagrams with PlantUML in IntelliJ IDEA

Many developers ask how to draw flowcharts or UML class diagrams; this article recommends the PlantUML plugin for IntelliJ IDEA to quickly create them.

What is PlantUML

PlantUML is an open‑source project that provides a complete textual language for describing UML relationship diagrams and generates the diagrams using the powerful Graphviz rendering engine. The resulting UML images can be exported as PNG or scalable SVG files.

Advantages of PlantUML

Fully text‑based editing, no drag‑and‑drop controls, automatic spacing, simple and attractive output.

Independent of any development platform; as long as the PlantUML JAR is available, diagrams can be generated.

Integrates with many text editors and IDEs such as IntelliJ IDEA, Eclipse, Notepad++ and others.

For Java developers who typically use IntelliJ IDEA, the following steps focus on using PlantUML within IDEA.

Install the PlantUML Plugin in IDEA

File → Settings → Plugins, search for "PlantUML", locate "PlantUML integration" and install it.

Install Graphviz on Your Computer

Download Graphviz from the official site (e.g., https://graphviz.gitlab.io/_pages/Download/windows/graphviz-2.38.msi).

Configure environment variables:

Add a variable GRAPHVIZ_HOME with the installation path, e.g., D:\WorkWare\Graphviz2.38. Then append %GRAPHVIZ_HOME%\bin to the Path variable and set GRAPHVIZ_DOT to %GRAPHVIZ_HOME%\bin\dot.exe.

Verify the configuration by opening a Windows command prompt and running dot -version; the version information should be displayed.

Configure Graphviz in IDEA

File → Settings → Other Settings → PlantUML.

Draw a Flowchart with PlantUML

Create a new .uml file in IDEA.

Enter PlantUML text, for example:

@startuml
Alice -> Bob: Authentication Request
Bob --> Alice: Authentication Response

Alice -> Bob: Another authentication Request
Alice <-- Bob: another authentication Response
@enduml

The diagram is rendered in real time on the right side.

If you prefer not to install Graphviz, you can use the Chrome extension "PlantUML Viewer" to edit PlantUML text and view diagrams directly in the browser.